2-allylic thio pyridine n-oxides



.U tfi S te Z-ALLYLIC THIO PYRIDINE N-OXIDES Jack Rockett, Metuchen, NJassignor to Olin Mathieson Chemical Corporation, New Haven, Conn., acorporation of Virginia No Drawing. Application January 6, 1958 SerialNo. 707,149

6 Claims. (Cl. 260-2943) wherein X represents hydrogen, halogen or analiphatic group containing from 1 to 5 carbon atoms.

It has been found that the compounds of the general formula displaybiological activity and, more particularly, that the compounds possesspesticidal properties. They have been found to be particularly effectivewhen used as fungicides for application to plant foliage. They can beemployed in any of the forms conventionally employed for the applicationof pesticides.

The compounds of the invention are readily prepared by the reaction of asuitable salt of Z-mercaptopyridinel-oxide, such as the sodium salt,with an allyl halide in a suitable solvent medium. While the use of ananhydrous aliphatic alcohol as the solvent is preferred, other inertpolar solvents, such as dioxane in which sodium pyridinethione is onlyslightly soluble and forms a thick suspension, can be used.

The compound referred to herein as Z-mercaptopyridine-l-oxide, althoughgenerally represented as:

N SH J, O

is more accurately represented as a tautometer of two possiblestructures, as follows:

I OH

aten

The synthesis of S-(Z-pyridyl-l-oxide) allyl and sub stituted allylsulfides and the biological testing thereof Patented Jan. 26, 1960 aremore fully illustrated by the following, non-limitative examples:

Example I A solution of 44.7 g. (0.3 mole) of the sodium salt ofZ-mercaptopyridine-l-oxide in 650 cc. of absolute ethanol was preparedand filtered into a flask. 22.9 g. (0.3 mole) of allyl chloride wasadded dropwise and the flask contents were then heated and stirred at31-34 for about 4 hours as a precipitate gradually formed. The flaskcontents were heated to 39 for another five hours and then heated atreflux temperatures for two hours. The solution was filtered and theethanol was distilled from the filtrate at reduced pressure. Theremaining oil crystallized, providing 38.6 g. of (2-pyridyll-oxide)allyl sulfide, a 77.1% yield. The product had a melting point of 7374 C.after it was recrystallized from benzene plus hexane.

Example II A solution of 44.7 g. (0.3 mole) of the sodium salt ofZ-mercaptopyridine-l-oxide was dissolved in 700 cc. of absolute ethanoland filtered into a reaction flask. To it was added 27.2 g. (0.3 mole)of methallyl chloride and the flask contents were stirred and heated to35 for five hours. A precipitate of sodium chloride formed gradually.Now the flask contents were heated to reflux temperature for five hours.The solution was filtered and the ethanol was distilled from thefiltrate at reduced pressure. 44.0 g. (.243 mole) of a clear oilremained, an 81.1% yield of (2-pyridyl-l-oxide) methallyl sulfide.

Example III A solution of 52.2 g. (0.35 mole) of the sodium salt ofZ-mercaptopyn'dine-l-oxide was suspended in 400 cc. of dioxane. Now 38.9g. (0.35 mole) of 2,3-dichloropropene were added dropwise at 35-40. Anice bath was applied intermittently to keep the temperature fromexceeding 40. When the addition was complete, the temperature was raisedto 90 and maintained for one hour. The reaction mixture was filtered andthe dioxane was distilled at reduced pressure. There remained 49.7 g.(0.247 mole) of a clear oil, a 70.5% yield of (Z-pyridyl-l-oxide)(2'-chloroallyl) sulfide.

The compounds of this invention are adapted to be employed for thecontrol of various pests, particularly of agricultural pests. Thecompounds, which in most cases are liquids, may be dispersed on an inertfinely divided solid and employed as a dust. Suitable solid carriers areclay, talc, bentonite, as well as other carriers known in the art (seeFrear, Chemistry of Insecticides, Fungicides and Herbicides). Thecompounds may also be applied as a spray in a liquid carrier either as asolution in a solvent or as a suspension in a non-solvent such as water.When applied as a suspension it may be desirable to incorporate wettingagents. The compounds of this invention may also be admixed withcarriers that are themselves active, such as other parasiticides,herbicides and fertilizers.

Foliage fungicide tests, as described in Phytopathology, volume 33,pages 627-632 (1943), and volume 37, pages 354-356 (1947), showed that aconcentration of 25 parts per million of S-(2-pyridyl-1-oxide) allylsulfide inhibited the germination of 97% of the spore of Monoliniafructicola, an organism which causes brown rot of stone fruits.

The foregoing test indicates the utility of the novel compounds of thisinvention as biologically active agents, particularly as displayinguseful fungicidal properties,

The invention having been disclosed what is believed to be new anddesired to be secured by Letters Patent is:

1. .A compound of the general formula:

wherein X is a member .selected from the group consisting of hydrogen,halogen and lower alkyl groups containingfrom 1.410 5 carbon atoms.

3. (2-pyridyl-l oxideymethallyl sulfide.

'4. (Z-pyridyld oxide) :l(2'-chloroal1y1) sulfide.

S. A process for the preparation of a compound of the formula definedinclaim 1 which comprises reacting a salt of Z-mercaptopyridine-l-oxidewith an allyl halide in an inert solvent medium, and recovering theproduct.

6. A process for the preparation of (Z-pyridyl-l-oxide)-allyl sulfidewhich comprises reacting the sodium salt of Z-mereaptopyridine-l-oxidewith allyl chloride in a reaction medium comprising absolute ethanol.

Tarbell et a1.: '3. Am. Chem. Soc., vol. 74, pp. 48-50 (1952).

1. A COMPOUND OF THE GENERAL FORMULA: